Filter suspension system for a modular air handling system

ABSTRACT

A modular air-cleaning apparatus for the treatment of contaminated air. The apparatus includes a plurality of modular units cooperatively interconnected, wherein the plurality of units includes at least one separator unit functioning on non-collisional principles and at least one filtration unit functioning on collisional principles. Each modular unit is constructed of a durable and machinable material that is capable of withstanding harsh environmental conditions of use and is formed in a rectangular shape around four corner posts. Each post possesses at least one exposed, outwardly-facing surface with a side margin parallel to a long dimension of the post. The posts aid both in establishing and maintaining a mechanical connection between the unit and another of the modular units with which it is in operable connection, and in enhancing structural and mechanical characteristics of the unit. The posts have a plurality of surface faces, wherein one or more of the faces is adapted for operative connection to another one of the modular units.

This is a Divisional of application Ser. No. 08/409,828, filed Mar. 23,1995.

TECHNICAL FIELD

This invention relates to a modular air cleaning system for removingunwanted materials from the air. More particularly, the presentinvention relates to a modular air cleaning system for the removal ofmaterials comprising both dry and moist contaminants from the air drawnfrom proximate a mechanical industrial process, especially a processthat utilizes a coolant liquid.

BACKGROUND OF THE INVENTION

There is a growing need to remove foreign contaminant material from theair from proximate a mechanical industrial process. Such material may beeither dry, as in the form of smoke, or moist, as in the form of a mist.Such contaminant materials are typically produced from the milling andshaping operations of materials such as metal and ceramics. Many of suchmaterials are being recognized as comprising a significant hazard toindividuals exposed thereto. A material that has come under intensescrutiny in the last few years is the machine oil used to cool toolsduring the milling and shaping of materials. Firms utilizing suchmilling and shaping operations are feeling a growing need to capturesuch materials proximate the source and remove them from the air.Regulations that govern such contaminants promise to grow more stringentas their full potential hazards are recognized.

The milling and shaping operations of mechanical industrial process maybe performed in newly constructed facilities, where the devices tocleanse the air are incorporated when the production line is first laiddown. The greater challenge is to capture such contaminant materialsproduced on production lines that exist in old facilities. When theproduction lines were laid down in such facilities, the need to captureand remove such materials from the air was not recognized. Accordingly,the production lines in such facilities typically have minimal floorspace available in which to install air cleansing devices. Accordingly,it is desirable that such cleansing devices have a minimal foot print inorder to be capable of being installed in the minimal floor spaceavailable or are adaptable to being installed in the truss space locatedabove the production line. Such requirements require an air cleansingsystem that has readily adaptable exterior dimensions and flexibility ofdesign in order to accommodate a wide variety of existing conditions ina facility that is already fully laid out.

It is desirable that an air cleaning system that is adaptable to beingreadily retrofitted in a facility with an existing production line becapable of relatively long continuous operation between requiredcleaning maintenance. This is especially true if the air cleaning systemis to be installed in the relatively inaccessible truss space of thefacility. Typically, such maintenance requires that the production linebe shut down while the air cleansers are cleaned. A preferred way tominimize such cleaning maintenance is to provide an upstream airfiltration unit that is resistant to clogging to substantially cleansethe air prior to filtration by a filter unit that is susceptible toclogging. Along with this, is the need for ease in changing filters. Itis desirable that such filters be changed readily from outside theconfines of the air cleanser. The necessity of having maintenancepersonnel enter the air cleansing system enclosure in order to changethe filters can be both dangerous and time consuming.

An air cleaning system produced by the assignee of the presentapplication is the HELI-FLO® System. The HELI-FLO® System consists of aninlet chamber, Helical Tubes/coalescing chamber, final filter chamberand fan, mounted in a single enclosure. Another cleaning system is thatdescribed in U.S. Pat. No. 4,216,003 to Diachuk. The gas cleaning systemis mounted in a unitary cabinet and has rails disposed proximate the topof the cabinet with upwardly directed pockets from which the filtercomponent depends. Neither the cabinet structure of the '003 patent northe mounting structure from which the filter component depends is orteaches the structure of the present invention.

SUMMARY OF THE INVENTION

The modular design of the modular air cleaning system of the presentinvention substantially meets the requirements previously set forthabove. The modular air cleaning system has modularity of design of thecomponents comprising the various units that make up the modular aircleaning system. The universal corner post design of the modular aircleaning system is utilized regardless of the size of the unit beingconstructed. The corner post of the modular air cleaning system isdesigned to absorb abuse, to be a lifting structure for lifting theunit, to be a mounting structure for mounting the various componentswithin the unit, and to be a support structure providing structuralintegrity to the unit. The corner post design is also capable of beingadapted for use in connecting sections of duct work.

A single latch design and hinge design is utilized on all access doorsof the various units comprising the modular air cleaning system. Asingle type and shape of gasket material is utilized universallythroughout the units making up the modular air cleaning system to sealthe unit cabinet structure, the access doors, and the filter componentsin the various units.

The modular air cleaning system has modularity of unit design built in.Such modularity of unit design provides for stacking of units tominimize the footprint of the modular air cleaning system. Additionally,the units of the modular air cleaning system may be oriented in line andmounted in the truss space above a production line or spaced apart andinterconnected by means of duct work. Additionally, specialized cleaningunits that are unique to the contaminated airstream that is beingcleansed are capable of being disposed between the units making up themodular air cleaning system.

To maximize the operational time between required cleaning maintenance,the modular air cleaning system utilizes a helical filtration unit. Suchfiltration unit is as detailed in U.S. Pat. No. 4,460,386, issued Jul.17, 1984, assigned to the assignee of the present invention andincorporated herein by reference. The helical filtration unit is highlyresistant to clogging and at the same time removes approximately 99% ofthe mist borne materials. A Hepa filter is utilized downstream of thehelical filtration unit. The Hepa filter is substantially protected fromcontamination by the helical filter unit. Accordingly, the componentsthat comprise the Hepa filter need be changed only at intervalstypically measured in months.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the modular air cleaning system of thepresent invention comprising the helical filter unit, the Hepa filterunit, and the fan and motor unit;

FIG. 2 is a schematic representation of the modular air cleaning systemwith a diffuser coil and absorber bed disposed between the helicalfilter unit and the Hepa filter unit;

FIG. 3 is a schematic representation of the modular air cleaning systemhaving a cooling water coil associated with the helical filter unit anda diffuser coil being disposed between the helical filter unit and theHepa filter unit;

FIG. 4 is a schematic representation of the modular air cleaning systemhaving a valve disposed between the helical filter unit and the Hepafilter unit for selectively discharging the cleansed air from thehelical filter unit to the outdoor environment;

FIG. 5 is a schematic representation of the modular air cleaning systemwherein a helical filter unit is associated with each machine operationand a single Hepa filter unit further filters the air received from theplurality of helical filter units;

FIG. 6 is an end view of the corner posts of two connected adjoiningunits of the modular air cleaning system;

FIG. 7 is an end elevational view of the corner post adapted to joinsections of duct work;

FIG. 8 is a side elevational view of the corner post as used at thelower right front of the helical filter unit with a portion of the postshell broken away;

FIG. 9 is a perspective view of a door latch;

FIG. 10 is a sectional view of an access door latch in a latchedposition;

FIG. 11 is a sectional view of a door latch in the unlatchedconfiguration;

FIG. 11a is a sectional view of the door latch actuator;

FIG. 12 is a perspective view of a door latch and an access door mountedon a hinge;

FIG. 13 is a top view of an access door and a hinge with the door in anopen position depicted in phantom;

FIG. 14 is a perspective view of an open door mounted on a hinge in andan open latch recessed in a recess formed between the corner post andthe access door;

FIG. 15 is a side elevational view of the Hepa filter mounting rack;

FIG. 15a is an end elevational view of a Hepa filter supporting roller;

FIG. 15b is a sectional view of the Hepa filter supporting roller takenalong the section lines 15b--15b of the FIG. 15a;

FIG. 16 is a side elevational view of two Hepa filters mounted withinthe Hepa filter unit in the sealed snubbed position with the over centersnubber levers in phantom;

FIG. 17 is a perspective view of the over center snubber arm and aportion of the Hepa filter mounting rack;

FIG. 17a is a side elevational view depicting the rotational action ofthe over center snubber levers;

FIG. 17b is a representation of the motion of the hinge point of theover center snubber levers;

FIG. 18 is a side elevational view of the Hepa filter in the lowered,released position and Hepa filter snubber levers;

FIG. 19 is a side elevational view of the release bar engaged with therear face of a Hepa filter;

FIG. 20 is a side elevational view of the release bar rear face engaginghook;

FIG. 21 is a perspective view of the gasket frame retaining the tab;

FIG. 22 is a perspective view of the gasket frame and Hepa filterpartially removed from the Hepa filter unit; and

FIG. 23 is a front view of a portion of adjacent Hepa filters depictingthe left Hepa filter in the snubbed position and the right Hepa filterin the released position;

FIG. 24 is a front view of a portion of the helical filter unit with aportion of the corner post broken away to view the helical filtersupport structure;

FIG. 24a is a front view of a portion of the helical filter unit with aportion of the corner post broken away to view the helical filtersupport structure in the sealed position;

FIG. 25 is a top view of the helical filter jacking unit;

FIG. 26 is a front view of the Hepa filter unit with the drip traydepicted in the lower portion thereof; and

FIG. 27 is a front view of the modular air cleaning system with aportion of the fan and motor unit broken away to show the fan.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the modular air cleaning system generally at 10. Themodular air cleaning system 10 has three major components; the helicalfilter unit 12, the Hepa filter unit 14, and the fan and motor unit 16.Each such units 12, 14, and 16 is an individual module, capable of beingjoined together in a plurality of selected configurations or employed ina plurality of selected spaced apart configurations connected by ductwork. Like numbers denote like components throughout the description ofthe various figures.

The helical filter unit 12 is formed in a generally rectangular shape,having a vertical corner post 18 at each corner thereof. The cornerposts 18 are joined by cross members 20 extending therebetween. Thecabinet walls 22 are affixed to the corner posts 18 and the crossmembers 20 by sheet metal screws. The cabinet walls 22 are preferablyformed of stainless steel sheet material. An air intake 24 is providedin the top of helical filter unit 12. Duct work (not shown) that conveysthe contaminant material laden air from proximate the machine operationto the modular air cleaning system 10 is typically coupled to the airintake 24. For use where the overhead space is limited, an alternativeside entry air intake is provided by removal of air intake panel 26,when desired. In such cases, the air intake 24 would typically be sealedoff by a panel similar to air intake panel 26. It should be noted thatair intake panel 26 is recessed, such that the outer surface of the airintake panel 26 is flush with the side surfaces of corner posts 18 and arecess is defined therebetween.

A side hinged access door 28 is provided in a front of the helicalfilter unit 12. The access door 28 facilitates the installation andremoval of a helical filter tray and visual inspection thereof. Fourlatches 30 are provided to effect an air tight seal between the accessdoor 28 and the cabinet wall 22.

In the configuration of FIG. 1, the helical filter unit 12 is bolted tothe Hepa filter unit 14. An air passageway (not shown) is defined in thelower portion of the adjoining walls (not shown) of the helical filterunit 12 and the Hepa filter unit 14 in order to accommodate the flow ofexhaust air from the helical filter unit 12 to the lower intake portionof the Hepa filter unit 14. It is understood that the helical filterunit 12 is spaced apart from the Hepa filter unit 14 with duct worktherebetween providing such air passageway in certain applications.

The Hepa filter unit 14 is generally rectangular in shape and is formedaround four corner posts 18. The walls (not shown) of the Hepa filterunit 14 are preferably formed of stainless steel sheets.

The front of the depicted embodiment of the Hepa filter unit 14 includestwo structural panels 32, extending between the corner posts 18, and twoaccess doors 34, 36. The front surface of the structural panels 32 andthe front surface of access doors 34, 36 are coplanar with the frontsurface of the two corner posts 18 on either side thereof, so that nostructural components extend beyond such plane. This structure alsodefines recesses along the side margins and top and bottom margins ofthe access doors 34, 36. The door hardware, including hinges and latches30 are mounted within such recesses. Such mounting results in nostructural protrusions beyond the plane defined by the front surface ofthe corner posts 18 and the front surface of the structural panels 32and access doors 34, 36.

The access door 34 is hinged at the bottom and provides access to thewaste and coolant collection area beneath the Hepa filters. The accessdoor 36 is hinged at the bottom and provides access to the Hepa filters.As will be seen, the Hepa filters may be readily removed and replacedthrough the access door 36 without the necessity of having themaintenance personnel enter the cabinet of the Hepa filter unit 14.

In the configuration depicted in FIG. 1, the fan and motor unit 16 isstacked on top of the Hepa filter unit 14. Such stacking minimizes thefootprint of the modular air cleaning system 10 in a desiredapplication. It is understood that the fan and motor unit 16 could aswell be mounted along side the Hepa filter unit 14 such that the helicalfilter unit 12, the Hepa filter unit 14 and the fan and motor unit 16are oriented in an in-line configuration. Such configuration minimizesthe heighth dimension of the modular air cleaning system 10 and isuseful for mounting the modular air cleaning system 10 in a space withlimited overhead dimensions such as in the truss space of a building,above a production line.

The fan and motor unit 16 is formed in a generally rectangular shape andhas the same length and width dimensions as the Hepa filter unit 14 tofacilitate the stacking of the fan and motor unit 16 thereon. Thestructure of the fan and motor unit 16 is also formed around four cornerposts 18. A joining air passageway (not shown) is formed between the topof the Hepa filter unit 14 and the bottom of the fan and motor unit 16in order to facilitate the flow of air therebetween. The fan of the fanand motor unit 16 acts to draw the contaminated air from the vicinity ofthe machine operation, through the helical filter, and through the Hepafilter to de exhausted as a clean air stream. A side panel 38, that isrecessed between the corner posts 18 on either side thereof, may beremoved to provide an air intake passageway, when the Hepa filter unit14 and the fan and motor unit 16 are oriented in a side by sideconfiguration.

Two side hinged access doors 40, 42 are provided in the front face ofthe fan and motor unit 16. The front surface of the access doors 40, 42is coplanar with the front surface of the corner posts 18 on either sidethereof. The hardware for hinging and latching the access doors 40, 42is mounted in the recesses formed between the doors 40, 42 and thecorner posts 18 such that no portion thereof breaks the plane formed bythe front surface of the corner posts 18.

In the preferred embodiment, one or more squirrel cage type fan motorsare mounted within fan and motor unit 16. An air exhaust 44 is definedin the top of fan and motor unit 16. An exhaust duct 46, depicted inphantom is affixed thereto for conveying the cleansed air from themodular air cleaning system 10. The exhaust duct 46 may be configuredsuch that the exhaust duct 46 exhausts the cleansed air within theconfines of the building within which the modular air cleaning system 10is mounted or the exhaust air may be exhausted outside such building, asdesired.

FIGS. 2-5 depict the flexibility that results from the modularity of themodular air cleaning system 10. In each figure, the modular air cleaningsystem 10 is comprised of at least the three modules comprising thehelical filter unit 12, the Hepa filter unit 14 and the fan and motorunit 16. Such modular units are spaced apart and connected by duct work48. In FIGS. 2 and 3, additional cleansing components have been added inorder to enhance the cleansing operation. Such additional cleansingcomponents are utilized particularly when the mechanical machineoperation results in the production of contaminants that have someunique cleansing requirements. In FIG. 2, a diffuser coil 50 andabsorber bed 52 have been disposed between the helical filter unit 12and the Hepa filter unit 14. The diffuser coil 50 is similar to thatused in refrigeration system and can condense certain materials out fromthe air flow. The absorber bed 52 may be of activated charcoal tofurther cleanse the air flow. In each case, the diffuser coil 50 and theabsorber bed 52 are housed in modular units having similar components asthe modular units 12, 14, and 16.

The configuration depicted in FIG. 3, a cooling water coil 54 has beenassociated with the helical filter unit 12. The water coil 54 acts tocool the air flow from the helical filter unit 12. Such cooled air flowincreases the efficiency of the diffuser coil 50.

In the configuration of the modular air cleaning system 10 depicted inFIG. 4, the modules that comprise the helical filter unit 12, the Hepafilter unit 14, and the fan and motor unit 16 are spaced apart andconnected by duct work 48. An air valve 56 has been disposed in the ductwork 48 between the helical filter unit 12 and the Hepa filter unit 14.Such air valve 56 selectively directs the air exhaust from the helicalfilter unit 12 to an outdoor fan 58 or to the Hepa filter unit 15. Thehelical filter unit 12 is a highly efficient unit that typically removesapproximately 99% of the unwanted material in the air flow. The airstream exhausted from the helical filter unit is safe to be exhausted tothe ambient air outside the facility in which the modular air cleaningsystem 10 is mounted. During periods of warm weather, it may bedesirable to exhaust such cleansed air outside. In this case, theoutdoor fan 58 provides the motor flow energy to draw the air throughhelical filter unit 12. When the weather is cooler, it may be desirableto retain the heated cleansed air within the facility. In such case, theair valve 56 is oriented to direct the exhaust from the helical filterunit to the Hepa filter unit 14. In this case the outdoor fan 58 isdeenergized in the fan and the fan and motor unit 16 is activated inorder to provide the motive force for drawing the contaminated airthrough the helical filter unit 12 and the Hepa filter unit 14.

The configuration depicted in FIG. 5 has a dedicated helical filter unit12 associated with each forming machine 60. The forming machine 60 maybe milling or shaping machines that utilize a machine oil as coolant.The coolant is removed from the vicinity of the forming machines eitherby flowing as droplets through the coolant scavenge lines 62 to thecoolant return 64 or being drawn off in a mist to the helical filterunit 12. The helical filter unit 12 removes a substantial portion of thecoolant from the air. Such coolant flows from the drain 29 of thehelical filter unit 12 through drain line 66 to the coolant return 64.The coolant in the coolant return 64 may then be cleansed and reused tocool the forming operations, as desired.

The air from the plurality of helical filter units 12 is drawn throughduct work 48 to Hepa filter unit 14 by fan and motor unit 16. Therelatively large Hepa filter unit 14 and fan and motor unit 16 isutilized to service the plurality of helical filter units 12.

FIG. 6 depicts the adjoined corner posts 18 of two joined modular unitsof a modular air cleaning system 10, such as the joined helical filterunit 12 and Hepa filter unit 14 as depicted in FIG. 1.

The corner posts 18 have two major components; channel 70 and post shell72. The channel 70 is preferably formed of a stainless steel materialand has a substantial thickness thereto in order to provide thenecessary structural support. The channel 70 may be approximately twotenths of an inch thick. Channel 70 is formed in a U shape, having threeclosed sides and an open side. As used in modular air cleaning system10, the open side of the corner posts 18 faces outward, toward the frontof the modular unit for the corner posts 18 that form the front cornersof the unit and toward the rear of the modular unit for the corner posts18 that form the rear corners of the unit.

In order to increase the structural integrity of the channel 70, aplurality of tie plates are welded to the channel 70. The tie plates 74are T shaped having a first planar member 76 shaped to substantiallyconform to the inner dimensions of the channel 70. A second planarmember 78 is oriented transverse to the first planar member 76 and issized to extend across the open side of the channel 70. The secondplanar member 78 has a heighth dimension that is preferablyapproximately two inches.

A tie plate 74 is disposed proximate the top of the corner post 18 andproximate the bottom of the corner post 18. A plurality of tie plates 74are disposed between such top and bottom tie plate 74, the number ofsuch tie plates depending upon the heighth of the corner post 18. Thetop and bottom tie plates 74 have an outwardly directed curled lip 80,curled lip 80 has threaded bores 82 formed therein. A cover plate 84that is substantially coextensive to the heighth dimension of the cornerpost 18 covers the open side of the channel 70 and is affixed to the lip80 of the top and bottom tie plates by machine screws 86. Cover plate 84is primarily decorative in nature.

A central bore 88 is defined in the first planar member 76 of each ofthe tie plates 74.

The post shell 72 substantially encloses the closed sides of channel 70.Post shell 72 is formed of substantially later cage steel than channel70 and is welded thereto. The post shell 72 additionally defines aninwardly directed component bearing section 90 that extends inward fromthe channel 70. The component section 90 provides suitable surfaces uponwhich to mount the various components forming the cabinets of thehelical filter unit 12, the Hepa filter unit 14, and the fan and motorunit 16, as will be described. The post shell 72 has curled ends 92 thatwrap around both ends of the open side of the channel 70. The curledends of post shell 72 meet the second planar member 78 of the tie plate74, defining a plane therewith and are joined thereto by a weldment. Thecover plate 84 overlies a portion of the curled ends 92 of the postshell 72.

In a preferred embodiment, a steel plate (not shown) having a thicknessof approximately one half inch is formed to conform substantially to theexterior shape defined by the post shell 72 and extending across theopen mount of channel 70. Such a plate is welded to both the top andbottom of corner posts 18. A bore is provided in such end plate that isin registry with central bore 88 of tie plate 74. Eyes for lifting theunit of modular air cleaning system 10 may be suitably installed in suchbore of the four corner posts 18 of a modular unit. Additionally, themodular unit may be affixed to the surface upon which the modular unitis standing by a bolt sunk into such surface and passing through suchbore of the end plate welded to the bottom of the corner posts 18.Further, the stacked modular units, such as the Hepa filter unit 14 andthe fan and motor unit 16, as depicted in FIG. 1, are fixedly joined atthe corner posts 18 thereof by a bolt that is passed through such boresof the end plate welded to the bottom of the stacked corner posts 18,such bores being brought into registry.

A common gasket shape, formed of a common material is used throughout toseal the inner compartments of the modular units that comprise thehelical filter unit 12, the Hepa filter unit 14, and the fan and motorunit 16. The gasket 94 is formed of a compressible, closed cellmaterial. The gasket 94 is formed in a generally L shape with the longerleg of the L shape having substantial thickness in comparison to theshorter leg of the L shape. A gasket channel 96, defined in the cornerpost 18, is formed cooperatively by gasket retainer 98 and a portion ofthe component bearing section 90 of the post shell 72. The gasketretainer 98 is formed in a generally L shape with a curved end. A firstleg 100 of the gasket retainer 98 is affixed to the component bearingsection 90 by fastener 102. The second leg 104 of gasket retainer 98 isthe curled end that is designed to compressibly engage the gasket 94.Such engagement retains the gasket 94 within the gasket channel 96during assembly of the modular unit of the modular air cleaning system10.

The access door 28 of the helical filter unit 12 is depicted in itsclosed and latched position. A door gasket channel 106 is formed at themargin of the access door 28. The door gasket channel 106 is formed inpart by bending the end margin of the front face 108 of the access door28 at a right angle thereto. An inner wall 109 of the access door 28forms the opposing side of the door gasket channel 106. Retainer strip110 is positioned between the right angle portion of front face 108 andinner wall 109. Machine screws 112 threaded into bores formed in theright angle portion of front face 108 bear upon the retainer strip 110,causing the retainer strip 110 to compressibly engage the gasket 94. Inthis manner, the gasket 94 is compressibly contained within door gasketchannel 106. When the access door 28 is latched, the gasket 94 issealingly, compressibly engaged with the abutting corner of thecomponent bearing section 90 of post shell 72.

A generally L shaped latch bracket 114 is affixed, as by welding or bymachine screws, to the right angle portion of front face 108 of accessdoor 28. The latch bracket 114 is compressibly engaged by the latch 30when the latch 30 is in the latched position. Such engagement results ina sealing engagement between gasket 94 and the component bearing section90 of post shell 72.

Still referring to FIG. 6, the structural panel 32 of the Hepa filterunit 14 is sealingly affixed to the component bearing section 90 of thepost shell 72 in a manner that is similar to the aforementioned accessdoor 28. A gasket 94 is retained within a panel gasket channel 116 bybeing compressed by the action of machine screws 112 acting on aretainer strip 110 mounted between an inner wall 109 and a right angleportion of the front face 108 of the structural panel 32. A mountingbracket 118 is welded to the component bearing section 90 the post shell72. A fastener 120 fixedly couples the structural panel 32 to thebracket 118. In so doing, the gasket 94 is sealingly compressed againstthe corner of the component bearing section 90 of the post shell 72.

FIG. 6 depicts the helical filter unit 12 joined to the Hepa filter unit14. To accomplish this, the interior sidewall 122 of the helical filter12 is abutted to the interior sidewall 124 of the Hepa filter unit 14. Arelatively lengthy fastener 126 is passed through bores that are formedin the channels 70 of the corner posts 18 of the helical filter unit 12and the Hepa filter 14 and the interior sidewalls 122, 124, which boresare in registry. To separate the helical filter unit 12 from the Hepafilter unit 14, two shorter fasteners 126 are utilized with one suchfastener 126 joining the interior sidewall 122 to the channel 70 to thecorner post 18 of the helical filter unit 12 in a similar fastener 126joining the sidewall 124 to the channel 70 of the corner post 18 of Hepafilter unit 14.

FIG. 7 is an adaptation of the gasket channel concept to join two ductwork sections. The duct sidewalls 130 and 132 have ends formed in a Ushape and abutted against one another. Brackets 134 form a respectiveduct gasket channel 136 in cooperation with the duct sidewalls 130, 132.The U shaped end of each of the duct sidewalls 130, 132 compressiblyengages the gasket 94, holding the gasket 94 in place during joining ofthe duct work sidewalls 130, 132. A bonding material 138 is disposedbetween brackets 134 and duct sidewalls 130, 132. Tightening of thethree fasteners 140 acts to compress both gaskets 94 and both of thecross sectional axis depicted, thereby effecting a seal along the jointbetween duct sidewalls 130, 132.

The latches 30 that are commonly used on the access doors of the modularunits are depicted in FIGS. 8-12. FIG. 8 depicts the latch 30 mounted inthe recess defined between the access door 28 and the corner post 18 ofthe helical filter unit 12. The latch 30 is depicted in its latchedconfiguration, compressibly engaging the latch bracket 114 of accessdoor 28.

The latch 30 is comprised of two major components; a latch frame 142 anda latch arm 144. The latch frame 142 is a generally L shaped piece ofsteel barstock. The long arm of the L shaped latch frame 142 is adaptedto lie flush on the cabinet wall 146 in the recess formed between thecorner post 18 and the access door 28. The latch frame 142 is maintainedin position by two cap screws 148 that pass through bores 150, formed inlatch frame 142, and bores 152, formed in the cabinet wall 146.

The short leg of the L shaped latch frame 142 has a rod bore 154 definedtherein. The end margin of the short leg of the latch frame 142 has anoutward bend that presents a ramp face 156 to the latch arm 144.

The latch arm 144 has four subcomponents; the latch arm body 158, theslide actuator 160, the latch rod 162, and the bracket engagingcompensator 164.

The latch arm body 158 has a hinged slot 166 that is adapted to slideover the hinge bracket 157. The latch arm body 158 is rotatably engagedwith the hinge bracket 157 by clevis pin 168.

The latch arm body 158 further has a central bore 170 defined therein.The central bore 170 has a depth equal to approximately one half thelength of the latch arm body 158. A threaded compensator bore 172 isoriented transverse to the central bore 170 and located approximatelymidway between the end of central bore 170 and the clevis pin 168. Asecond compensated bore 172a may be formed alongside compensator bore172, as desired.

The latch rod 162 is slideably disposed within the central bore 170. Acoil spring 174 is disposed between the inner end of the latch rod 162and the interior end of the central bore 170. The spring 174 is held incompression and acts to bias the latch rod 162 to the left, as depictedin FIGS. 10 and 11. In the latched position, as indicated in FIGS. 9 and10, the latch rod 162 passes through the rod bore 154, thereby holdingthe latch arm 144 in the latched position.

The slide actuator 160 is slideably mounted on top of the latch arm body158. The slide actuator 160 is fixedly coupled to the latch rod 162 bytwo cap screws 176. The cap screws 176 pass through an elongated racetrack shaped slot 178 formed in the latch arm body 158. The slot 178intersects the rod bore 154. The cap screws 176 pass through the slot178 and are threaded into bores 180 formed in latch rod 162. The slot178 accommodates lateral movement of the slide actuator 160 with respectto the latch arm body 158. Sliding motion to the right, as indicated byarrow 182 in FIG. 11, acts to disengage the latch rod 162 from the rodbore 154 and further compresses spring 174.

A locking screw 184 is threadedly engaged in a bore 188 formed in slideactuator 160. In the latched position as indicated in FIGS. 10 and 11a,the locking screw 184 is positioned over a recess 186 formed in thelatch arm body 158. Turning the locking screw 184 in to engage therecess 186, as indicated in FIG. 11a, locks the slide the actuator 160in the latched position, preventing an inadvertent unlocking actuation,the unlocking actuation being as indicated in FIG. 11.

The bracket engaging compensator 164 and the second optional bracketengaging compensator 164a, depicted in phantom, are threadedly engagedin compensator bores 172, 172a respectively. The compensators 164, 164ahave spring loaded plungers 190 enclosed therein. The plungers 190 arefree to translate within the compensators 164, 164a. The plungers 190are biased in an extended position. The spring loaded plungers 190compressively engage the latch 114 of the door 28, holding the accessdoor 28 in a sealed and closed position on the latch 30 is in thelatched configuration as indicated in FIGS. 9 and 10.

In operation, a latch 30 is unlatched by manually sliding the slideactuator 160 to the right as indicated by arrow 182 in FIG. 11. Thisaction disengages the latch rod 162 from the rod bore 154. Once thelatch rod 162 is disengaged, the latch arm 144 is free to rotate asindicated by arrow 192. Such rotation eventually disengages the springloaded plungers 190 from the latch bracket 114. The design of the latch30 is such that the latch arm 144 may be rotated a full 180° from thelatched position so that the latch arm 144 is again fully containedwithin the recess formed between the access door 28 and the corner post18.

To place the latch 30 in a latched configuration, the access door 28 isfirst positioned in the closed position. The latch arm 144 of the latch30 is then rotated in a direction opposite to the arrow 192. The spring174 urges the latch rod 162 to its full left position as indicated inFIG. 10. As the rotation is continued, the end of the latch rod 162bears upon the ramp base 156. Continued pressure on the latch arm 144increases the compression of spring 174 as the latch rod 162 rides downthe ramp face 156 and is forced to translate to the right. Prior to thelatch rod 162 engaging the rod bore 154, the spring loaded plungers 190again come in contact with the latch bracket 114 of the access door 28,thereby forcing the access door 28 into its sealed, closed position.

The access doors 28 are typically maintained in a closed position formany months at a time. The access doors 28 may then be opened for a veryshort period of time, as for example to perform a visual check of theinterior components of the modular unit or to replace an expandablefilter component. A characteristic of the closed cell material used inthe gaskets 94 is that such gaskets 94 take a set after a period of timeof being compressed. Due to the closed cell nature of the gaskets 94, ittakes a substantial period of time, extending over as much as severalhours, to remove this set from the gasket 94 once the compressive forcesare removed. In such circumstances, the gasket 94 of the access door 20may still have its previous set when it is time to again close theaccess door 28. In such a situation, an effective seal between thegasket 94 of the access door 28 and the compressively engaging portionof the unit may not be possible. To account for this condition, thespring loaded plungers 190 of the bracket engaging compensators 164,164a extend and compressively engage the latch bracket 114, even thoughthe gasket 94 of the access door 28 still has its compressed set. Over aperiod of time after the access door 28 is closed, the set of the gasket94 is adjusted responsive to the compressive forces exerted thereon, theforce exerted by the spring loaded plungers 190 and the countering forceexerted by the gasket 94 reach a point of equilibrium in which thegasket 94 is held in its desired compressive sealing state.

FIGS. 12 and 13 depict the suspension and latching hardware of the sidehinged access door 28 with respect to the latch 30. The latch 114 isdepicted as affixed to the recess side 200 of access door 28. The latchbracket 114 is affixed in such position by machine screws 202. Thelatching portion of the latch bracket 114 extends to the left fromaccess door 28 as depicted in FIG. 12 and underlies the latch arm 144 ofthe latch 30. The hinge 204 is a clevice-type hinge. The clevice bracket206 is affixed to the component bearing section 90 of the corner post18. The clevice bracket 206 has a groove 208 defined therein. The hingetongue 210 is affixed to the access door 28. An elongated pin slot 212is defined in both ears of the clevice bracket 206. The pin 214 ispassed through the pin slots 212 and a bore formed in the hinge tongue210. The elongated pin slot 212 permits the access door 28 to movelaterally with respect to the cabinet wall 146.

FIG. 14 depicts a bottom hinged access door 40 or 42 of the typeutilized on a Hepa filter unit 14. A similar clevice hinge 204 isutilized to support the access door 40.

In operation, to open an access door 28, 40, the latch 30 is unlatchedas previously described and rotated as indicated by the arrow 216 inFIG. 12 to the open position in which the latch 30 lies in the recess.The latch 30, as depicted in FIG. 14, is shown in the fully openedposition resting within such recess. The access door 28, 40 can then bepulled away from its seated closed position by sliding the pin 214 inthe pin slot 212 to its furthest outward position as depicted in FIGS.13 and 14. This action frees the gasket 94 from its seat and allowsopening rotation of the access door 28, 40 without scuffing the gasket94 and free of interference by the opened latch 30 positioned within therecess.

In closing the access doors 28, 40, the access door 28, 40 is rotated tothe closed position, but is spaced slightly apart from engagement withthe cabinet wall 146. In this manner, the access door 28, 40 is alignedin its closed position without scuffing the gasket 94. As the latches 30are then closed, compression of the gasket 94 occurs and the door movesinward to its seated position against the cabinet wall 146. In suchmovement, the pin 214 of the hinges 204 moves inward in the pin slot212.

Various components utilized for supporting and replacing the Hepafilters 220 within the Hepa filter unit 14 are depicted in FIGS. 15-20.The Hepa filters 220 are the only components of the modular air cleaningsystem 10 that are expendable and require periodic replacement. Becauseof the very thorough cleansing action of the helical filter unit 12, theHepa filters 220 typically may be used for a number of months or evenmore than a year before replacement is necessary. It is understood thatthe time interval between replacement is, however, dependant upon thenature and quantity of unwanted contaminant materials that are borne bythe air flow.

The Hepa filter unit 14 in the depicted preferred embodiment is designedto hold four commercially available Hepa filters 220. The Hepa filters220 are mounted in pairs with two pairs being disposed in racks that areabreast of one another.

As depicted in FIG. 15, the Hepa filters 220 are supported by a rollerplate 222. A plurality of rollers 224 are affixed to the roller plate222 by nuts 226. The roller plates 222 on opposite sides of the Hepafilters 220 each have inwardly directed rollers 224 upon which the lowermargin of the Hepa filters are supported.

The rollers 224 have a roller cylinder 228. Are preferably made ofbrass. The roller cylinder 228 is mounted concentric with an axle 230and rides on circular bearings disposed between the axle 230 and theinner surface of the roller cylinder 228. The cap 234 is affixed to theend of the axle 230 to limit the lateral motion of the roller cylinder228. The opposing end of the axle 230 from the cap 234 is threaded toreceive the nut 226. The roller plate 222 is mounted such that theroller plate 222 is capable of both vertical and horizontal translation.

The flow of air to be cleansed is drawn in through the bottom of theHepa filters 220 and exhausted from the top thereof. Accordingly, a sealis needed around the top margin of the pair of Hepa filters 220 in orderto force the airstream to pass through the Hepa filters 220. Tofacilitate such sealing, a removable gasket frame 236 is positionedabove the Hepa filters 220. The gasket frame 226 has a downward directedgasket 94 positioned to mate with the gasket that is positioned aroundthe top margin of each of the Hepa filters 220. The gasket frame 236 isalso seated against frame support 238. The frame support 238 is boltedto cross members 242 of the Hepa filter unit 14.

The Hepa filters 220 must be free of a sealing engagement with thegasket 94 of the gasket frame 236 during removal and installation ofsuch Hepa filters 220. Accordingly, a snubbing mechanism is provided toengage and disengage the Hepa filters 220 from the gasket 94. Eachroller plate 222 has associated with it a front and a back over centerlever 246. By providing such lever 246 at both and the front and theback of the Hepa filter unit 14, the Hepa filters 220 may be removed andinstalled from either the front or the back of the Hepa filter unit asdesired.

The over center levers 246 each have two pivot points; a lower anchorpivot point 248 and an upper roller pivot point 250. The pivot points248, 250 are spaced apart on the over center lever 246. Accordingly,rotation of the over center lever 246 about the anchor pivot point 248results in the roller pivot point 250 translating in an upwardlydirected arc about the anchor pivot point 248.

The snubbing mechanism 244 is best depicted in FIGS. 15a and 17. Theanchor pivot point 248 is formed by a bolt passing through a bore (notshown) located proximate the lower margin of the over center lever 246.The bolt 252 is anchored in the cross member supporting structure 242. Aspacer bushing 254 is disposed on the bolt between cross member 242 andover center lever 246. A nut 256 is threaded onto the bolt 252. Sincethe bolt 252 is anchored in the cross member 242, the anchor pivot point248 is fixed in position with respect to the Hepa filter unit 14.

A bracket 258 is affixed to the roller plate 222. The roller pivot point250 is formed by a nut and bolt that pass through bores formed in thebracket 248 and the over center lever 246. The over center lever 246 isa transverse flat plate at the second end thereof that comprises ahandle 262.

FIGS. 17a and 17b are referred to for the operation of snubbingmechanism 244. As previously indicated, the Hepa filters 220 can beloaded from either the front or the rear sides of the Hepa filter unit14. Assuming that the Hepa filters have been loaded from the left sideas depicted in FIG. 17a, both of the over center levers 246 arepositioned in their left most rotation. This position corresponds to theposition 264a of the rollers 224 as depicted in FIG. 17b. To snub theHepa filters up tight against the gasket 94 of the gasket frame 236,hand pressure is exerted on the handle 262. This pressure causes therotation of over center levers 246 to the right to the upright position.Such rotation causes the rollers 224 to translate to the right and torise. At the apex of the rotation, as indicated in the snubbed position266, the Hepa filters are snubbed and sealed against the gasket 94. Inthe instance in which the Hepa filters 220 have been put in place on theright side as indicated in FIG. 17a, the two over center levers 246would be in their right most disposition. This position corresponds tothe free position 264b of the rollers 224 as indicated in FIG. 17b.Snubbing the Hepa filters is accomplished by putting rotational pressureon the handle 262 of the right most over center lever 246. The resultingrotation causes the Hepa filter bearing rollers 224 to translate to theleft from the free position 264b to the snubbed position 266.

The Hepa filters 220 weight approximately 30 pounds when installed cleanand may weight as much as 50 pounds when removed after filters unwantedmaterial from the air stream. Referring to FIGS. 18-20, a removal device270 is positioned beneath the rollers 224 supporting the Hepa filters220. The removal device 270 is comprised of an elongated rod 272. Therod 272 is translatably borne in end brackets 274. A T-shaped handle 284is affixed to a first end of the rod 272. A filter engaging finger 286is affixed to the rod 272 proximate the second end of the rod 272. Thefilter engaging finger 286 projects upward behind the Hepa filter 220. Astop bracket 288 supports the rod 272 and is positioned approximatelyone-third of the rod's length from the handle 284.

In operation, a maintenance person grasps the T handle 284 and pulls tothe left as depicted in FIGS. 18-20. The filter engaging FIG. 286 abutsthe rearmost Hepa filter 220 and advances both of the Hepa filters 220towards the left towards the maintenance person. In FIG. 19, the firstHepa filter 220, which is depicted in phantom, of the pair of Hepafilters 220 has been removed. At this point the filter engaging finger286 abuts the stop bracket 288, preventing the further advancement ofthe second Hepa filter 220 toward the maintenance person. Stop bracket288 prevents the maintenance person from advancing the second Hepafilter 220 to the point where it falls free from Hepa filter unit 14 topotentially injure the maintenance person.

When the Hepa filters 220 are in the free position 264a as depicted inFIG. 18, the gasket frame 236 is free of compressive engagement with theframe support 238. In order to prevent the gasket frame 236 from pullingout of the Hepa filter unit 14 when the Hepa filters 220 are removed, astay bracket 290 is utilized. The stay bracket 290 is held in place by athumb screw 292.

As indicated in FIG. 22, the gasket frame 236 is readily removable fromthe Hepa filter unit 14 by loosening the stay bracket 290 by means ofthe thumb screw 292 and rotating the stay bracket 290 out of the waygasket frame 236 is depicted as being partially withdrawn from Hepafilter unit 14 and simply continuing to pull on the gasket frame 236will result in its removal from the Hepa filter unit 14. Such removalfacilitates the replacement of gasket 94 within the gasket frame 236, asneeded.

As depicted in FIG. 23, the gasket frame 236 is held loosely in placewithin Hepa filter unit 14 by a two-pronged bracket 294. When the gasketframe 236 is inserted into the Hepa filter unit 14, the upper prong 296of the bracket 294 is positioned above the retaining bracket 300 and thelower prong 298 of bracket 294 is positioned beneath the retainingbracket 300. The retaining bracket 300 is fixedly coupled to the crossmember 242 of the Hepa filter unit 14.

The right Hepa filter 220 as depicted in FIG. 23 is in its lowered, freeposition. In such position, the gasket frame 236 drops down and issupported by the upper prong 296 resting on the retaining bracket 300.

The Hepa filter 220 as depicted on the left in FIG. 23 is in its up andsnubbed position. Accordingly, the over center lever 246 is depicted inits upper most position. When the Hepa filter 220 is snubbed up againstthe gasket frame 236, the gasket frame 236 is supported by thecompressive forces exerted by the Hepa filter 220. In such condition,the two-pronged bracket 294 plays no role in supporting the gasket frame236.

The disposition of the helical filter tray 302 within the helical filterunit 12 is depicted in FIGS. 24-25. The helical filter tray 302 iscomprised of an array of helix tubes 304. Each of the helix tubes 304 ispreferably formed of a steel material and has a helical pathway (notshown) defined therein. The helix tubes 304 are made in accordance withU.S. Pat. No. 4,460,386. Depending on the application, a helical filtertray 302 may include twenty or more helix tubes 304.

The helical filter tray 302 is supported on both sides by a tray frame306. The tray frame 306 is a generally U-shaped channel and has anupwardly directed gasket tang 308. The gasket tang 308 actscooperatively with the backing plate 310 to form a gasket channel 312.

A gasket 94 is disposed within the gasket channel 312. The gasket 94 isheld within the gasket channel 312 by a retainer strip 110. The retainerstrip 110 acts to compress the gasket 94 between the retainer strip 110and the backing plate 310 by means of machine screws 112 acting on theretainer strip 110.

The backing plate 310 is an extension of the tray 314 from which thearray of helix tubes 304 depend. When viewed from the top, the tray 314has an appearance not unlike a baking utensil for cupcakes, having aseries of geometrically arranged depressions, comprising the helix tubes304, disposed within the tray 314.

A step support 316 is formed at both sides of the opening in the helicalfilter unit 12 in which the helical filter tray 302 is disposed. Theunderside of the tray frame 306 rests on and is supported by the stepsupport 316 to facilitate sliding the helical filter tray 302 into thehelical filter unit 12. A jacking unit 318 is positioned on either sideof the helical filter tray 302. The jacking unit 318 depends from a bore320 formed in the cross member 242.

The jacking unit 318 is comprised of an elongated threaded bolt 322. Thebolt 322 passes through the bore 320 and is threadedly engaged with nut324. A washer 326 disposed between the nut 324 and the upper surface ofthe cross member 242 assists in supporting the jacking unit 318.

A U-shaped support bracket 330 has a bore 332 defined therein. A nut 334is affixed to the support bracket in registry with the bore 332 as bywelding. The bolt 322 is passed through the bore 332 and threaded intonut 334.

The jacking unit 318 is disposed approximately half way into the openingin the helical filter unit 12 in which the helical filter tray 302 isinstalled. Accordingly, during installation, as the helical filter tray302 is advanced into such opening, the undersigned of the tray frame 306rides on top of the upper side of the support bracket 330. When thehelical filter tray 302 is fully advanced into the opening defined inthe helical filter unit 12, the nut 324 is rotated thereby drawing thehelical filter tray 302 up into the position as depicted in FIG. 24a.Such action causes the gasket 94 to be seated on the underside of thecross member 242. It should be noted that the gasket is substantiallyisolated by surrounding structure from coming into contact with thecontaminated air flow that passes through the helix tubes 304 duringoperation.

FIG. 26 depicts Hepa filter unit 14. A drip tray 336 is disposed at thebottom of Hepa filter unit 14. A similarly constructed drip tray 336 isdisposed in the bottom portion of the helical filter unit 12.

The drip tray 336 is comprised of a stainless steel tray having inwardlysloping sides 338 coupled to a sloped floor 340. The sloped floor 340slopes toward the drain 33 so that liquid material captured by the driptray 336 is free to flow from the drain 33. It should be noted that asimilar drain 33 is formed on the rear side of the Hepa filter unit 14.

FIG. 27 depicts the modular air cleaning system 10. A portion of the fanand motor unit 16 is broken away to show a conventional squirrel-cagetype fan 342. The fan 342 has an axially oriented inlet 344 and anexhaust 346 that exhausts out the top of fan and motor unit 16. Arotor-type fan blower (not shown) rotates about the rotor axle 348.

While there has been shown and described the preferred embodiment of themodular air cleaning system of the present invention, it is understoodthat changes in the structures and sizes and materials may be made bythose skilled in the art without departing from the present invention.The present invention is defined in the following claims.

I claim:
 1. A substantially sealed modular air handling system having aplurality of modules enclosing a plurality of air handling units, eachof said modules having generally parallelpiped shaped cabinetry havingtwo opposed sides and opposed front and rear faces, having a pluralityof common components designed to seal and readily math the modules toone another in a plurality of selected configurations, to provide readyaccess to the air handling units enclosed therein via the front and rearfaces thereof and to present an external surface that is substantiallyfree of protruding devices which may pose a safety hazard to personnel,wherein at least one of the air handling units comprises a plurality ofreplaceable filters and wherein a selected one of the common componentsis a filter suspension system, the filter suspension system beingdisposed within the cabinetry of the modular air handling system, thereplaceable filters having a generally rectangular frame defining an airpassage therethrough and presenting a filter upper margin and a sealinggasket disposed integral with the frame, and having filtering componentsdepending from said upper margin, the filtering components presenting afilter lower margin, the filter suspension system comprising:a pair ofspaced apart roller plates, having a plurality of inwardly directedrollers designed to rollingly engage and support the filter lowermargin; and a respective over center actuator operably coupled to thecabinetry of the modular air handling system and to each of rollerplates, the actuator being selectively positionable between a first freeposition wherein the roller plates are in a lowered disposition and eachof said replaceable filters may be freely rolled into and out of thecabinetry of the modular air handling system on said inwardly directedrollers, and a second snubbed position wherein each of said replaceablefilters is in a raised disposition compressively supported by therollers.
 2. A substantially sealed modular air handling system asclaimed in claim 1 wherein each respective over center actuator pivotsabout a first pivot point operably coupling said respective over centeractuator to the cabinetry of the modular air handling system, furtherwherein each of said filter suspension system roller plates is operablycoupled to a respective over center actuator at a second pivot pointradially separated from the first pivot point, whereby rotation of theover center actuator about the first pivot point results in the secondpivot point traversing an upwardly directed arc, the over centeractuator being in the second snubbed position at an uppermost pointalong the arc and being in the first free position at both ends of theare, such that the actuators may be accessed from the front and rearfaces of the cabinetry to selectively position the actuators between thefirst free position and the second snubbed position.
 3. A substantiallysealed modular air handling system as claimed in claim 1 wherein saidfilter suspension system further includes a removal rod slideablydisposed proximate the lower margin of the replaceable filters tofacilitate the removal of the replaceable filters from the cabinetry ofthe modular air handling system, the removal rod having an arm forengaging the replaceable filters proximate the lower margin thereof anda stop whereby the replaceable filters may be withdrawn from thecabinetry of the modular air handling system only to a point short ofwhere an imbalance in the replaceable filters would cause thereplaceable filters to fall free of the cabinetry of the modular airhandling system.
 4. The air handling system of claim 2 further includingsecond over center actuators operably coupled to the cabinetry of themodular air handling system and each of the roller plates to facilitateremoval and replacement of the replaceable filters from the front andrear faces of the air handling unit as desired.
 5. The air handlingsystem of claim 2 wherein the generally rectangular frame of thereplaceable filter is separable from the replaceable filter, the framebeing separably removable from the module cabinetry to facilitateremoval and replacement of the disposed integral therewith.
 6. The airhandling system of claim 5 further including a stay bracket, the staybracket having a first, proximate end operably, pivotally coupled to themodule cabinetry and a second, distal end for selective engagement withthe frame of the replaceable filter.
 7. The air handling system of claim5 wherein the generally rectangular frame has an outwardly directedsupport bracket disposed along each of two opposed sides thereof, thesupport brackets overlying a retaining bracket disposed along each ofthe two opposed sides and being fixedly coupled to the module cabinetry,the support brackets being in supportive engagement with the respectiveretaining brackets when the roller plates are in the lowereddisposition.